Intermediate Algebra for College Students (7th Edition)

Published by Pearson
ISBN 10: 0-13417-894-7
ISBN 13: 978-0-13417-894-3

Chapter 3 - Section 3.3 - Systems of Linear Equations in Three Variables - Exercise Set - Page 216: 30

Answer

$\{(-3,0,2)\}$.

Work Step by Step

The given system of equations are. $\Rightarrow \frac{x+3}{2}-\frac{y-1}{2}+\frac{z+2}{4}=\frac{3}{2}$ Multiply both sides by $4$. $\Rightarrow 4\cdot \left (\frac{x+3}{2}-\frac{y-1}{2}+\frac{z+2}{4}\right )=4\cdot \frac{3}{2}$ Apply distributive property. $\Rightarrow 2x+6-2y+2+z+2= 6$ $\Rightarrow 2x-2y+z+10= 6$ Add $-10$ to both sides. $\Rightarrow 2x-2y+z+10-10= 6-10$ Simplify. $\Rightarrow 2x-2y+z= -4$...... (1) $\Rightarrow \frac{x-5}{2}+\frac{y+1}{3}-\frac{z}{4}=-\frac{25}{6}$ Multiply both sides by $12$. $\Rightarrow 12\cdot \left (\frac{x-5}{2}+\frac{y+1}{3}-\frac{z}{4}\right )=-12\cdot \frac{25}{6}$ Apply distributive property. $\Rightarrow 6x-30+4y+4-3z= -50$ $\Rightarrow 6x+4y-3z-26= -50$ Add $26$ to the both sides. $\Rightarrow 6x+4y-3z-26+26= -50+26$ Simplify. $\Rightarrow 6x+4y-3z= -24 $...... (2) $\Rightarrow \frac{x-3}{4}-\frac{y+1}{2}+\frac{z-3}{2}=-\frac{5}{2}$ Multiply both sides by $4$. $\Rightarrow 4\cdot \left (\frac{x-3}{4}-\frac{y+1}{2}+\frac{z-3}{2}\right )=-4\cdot \frac{5}{2}$ Apply distributive property. $\Rightarrow x-3-2y-2+2z-6= -10$ $\Rightarrow x-2y+2z-11= -10$ Add $11$ to both sides $\Rightarrow x-2y+2z-11+11= -10+11$ Simplify. $\Rightarrow x-2y+2z= 1$...... (3) Multiply equation (1) by $3$ and add to equation (2). $\Rightarrow 3(2x-2y+z)+6x+4y-3z= 3(-4)-24$ Apply distributive property. $\Rightarrow 6x-6y+3z+6x+4y-3z= -12-24$ Add like terms. $\Rightarrow 12x-2y= -36$ ...... (4) Multiply equation (1) by $-2$ and add to equation (3). $\Rightarrow -2(2x-2y+z)+x-2y+2z= -2(-4)+1$ Apply distributive property. $\Rightarrow -4x+4y-2z+x-2y+2z=8+ 1$ Add like terms. $\Rightarrow -3x+2y= 9$ ...... (5) Add equation (4) and (5). $\Rightarrow 12x-2y-3x+2y= -36+9$ Simplify. $\Rightarrow 9x= -27$ Divide both sides by $9$. $\Rightarrow \frac{9x}{9}= \frac{-27}{9}$ $\Rightarrow x=-3$ Plug the value of $x$ into equation $5$. $\Rightarrow -3(-3)+2y= 9$ Simplify. $\Rightarrow 9+2y= 9$ Subtract $9$ from both sides. $\Rightarrow 9+2y-9= 9-9$ Simplify. $\Rightarrow 2y= 0$ Divide both sides by $2$. $\Rightarrow \frac{2y}{2}= \frac{0}{2}$ Simplify. $\Rightarrow y= 0$ Plug the values of $x$ and $y$ into equation (1). $\Rightarrow 2(-3)-2(0)+z= -4$ Simplify. $\Rightarrow -6+z= -4$ Add $6$ to both sides. $\Rightarrow -6+z+6= -4+6$ Simplify. $\Rightarrow z= 2$ The solution set is $\{(x,y,z)\}=\{(-3,0,2)\}$.
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